... concentrated as animals feed on plants and are consumed in turn by other animals. When they reach high levels in the body, heavy metals can be immediately poisonous, or can result in long-term ... moderately pure, and they cannot survive if their water is loaded with toxic chemicals or harmful micro-organisms. If severe, water pollution can kill large numbers of fish, birds, and other animals, ... chemicals are biodegradable and quickly decay into harmless or less harmful forms, while others are non-biodegradable and remain dangerous for a long time. Heavy metals, such as copper, lead, mercury,...